A Single All‐Fiber Platform for Switchable Supercontinuum and Few‐Cycle Pulse Generation

ABSTRACT Ultrafast laser sources are the cornerstone of advancements in diverse fields such as precision metrology, biomedical imaging, and attosecond science. However, the development of compact, multifunctional platforms that combine high performance with robust integration remains a key challenge. Here, we demonstrate an all‐fiber‐integrated platform capable of generating either an octave‐spanning coherent supercontinuum or few‐cycle pulses by simply controlling the length of spliced highly nonlinear fiber (HNLF). Seeded by a home‐made femtosecond fiber laser, the system utilizing a 0.12 m HNLF generates a highly coherent supercontinuum spanning 400–2400 nm. To the best of our knowledge, this represents the first femtosecond‐pumped, visible coherent supercontinuum generated within an all‐fiber structure. Alternatively, employing a 0.02 m HNLF enables nonlinear compression to high‐fidelity 22.4 fs pulses. This duration constitutes the shortest pulse achieved to date from a fully fiber‐integrated system. The source exhibits excellent stability (0.12% RMS power fluctuation) and near‐diffraction‐limited beam quality (M 2 < 1.15). This work provides a robust and flexible architecture, delivering record‐level performance for applications requiring either ultra‐broadband coherence or few‐cycle pulses in a single, fully integrated format.